﻿using System;
using Windows.ApplicationModel;
using Windows.ApplicationModel.Activation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

// The Blank Application template is documented at http://go.microsoft.com/fwlink/?LinkId=234227

namespace WindowsStoreApp
{
   /// <summary>
   ///    Provides application-specific behavior to supplement the default Application class.
   /// </summary>
   sealed partial class App
   {
      /// <summary>
      ///    Initializes the singleton application object.  This is the first line of authored code
      ///    executed, and as such is the logical equivalent of main() or WinMain().
      /// </summary>
      public App()
      {
         InitializeComponent();
         Suspending += OnSuspending;
      }

      /// <summary>
      ///    Invoked when the application is launched normally by the end user.  Other entry points
      ///    will be used when the application is launched to open a specific file, to display
      ///    search results, and so forth.
      /// </summary>
      /// <param name="args">Details about the launch request and process.</param>
      protected override void OnLaunched(LaunchActivatedEventArgs args)
      {
         var rootFrame = Window.Current.Content as Frame;

         // Do not repeat app initialization when the Window already has content,
         // just ensure that the window is active
         if(rootFrame == null)
         {
            // Create a Frame to act as the navigation context and navigate to the first page
            rootFrame = new Frame();

            if(args.PreviousExecutionState == ApplicationExecutionState.Terminated)
            {
               //TODO: Load state from previously suspended application
            }

            // Place the frame in the current Window
            Window.Current.Content = rootFrame;
         }

         if(rootFrame.Content == null)
         {
            // When the navigation stack isn't restored navigate to the first page,
            // configuring the new page by passing required information as a navigation
            // parameter
            if(!rootFrame.Navigate(typeof(MainPage), args.Arguments))
            {
               throw new Exception("Failed to create initial page");
            }
         }
         // Ensure the current window is active
         Window.Current.Activate();
      }

      /// <summary>
      ///    Invoked when application execution is being suspended.  Application state is saved
      ///    without knowing whether the application will be terminated or resumed with the contents
      ///    of memory still intact.
      /// </summary>
      /// <param name="sender">The source of the suspend request.</param>
      /// <param name="e">Details about the suspend request.</param>
      private void OnSuspending(object sender, SuspendingEventArgs e)
      {
         SuspendingDeferral deferral = e.SuspendingOperation.GetDeferral();
         //TODO: Save application state and stop any background activity
         deferral.Complete();
      }
   }
}